The air pollution problems inherent in the operation of gasoline fueled and diesel oil fueled internal combustion engines are well known. For this reason various emission control devices are presently in use, and indeed are often required by governmental regulations, to reduce the amount of pollutants discharged into the atmosphere by internal combustion engines. These emission control devices, however, only remove a portion of the pollutants and are subject to deterioration with the passage of time. Also, they often hinder engines from operating at peak efficiencies.
Natural gas is today sometimes used as a substitute fuel for gasoline and diesel oil. It has the capability of producing less combustion pollutants and for decreasing engine operating costs without complex emission control devices. Obviously, its expanded use would also reduce the rate of world fossil fuel consumption.
As the transportation infrastructure of today does not include large numbers of widely disbursed retail suppliers of natural gas for vehicles in many countries, it is not practical to produce vehicles that are fueled solely by gaseous fuels like natural gas due to range limitations. To evolve towards such it is more practical to equip vehicles to operate with a supply of both a liquid fuel such as gasoline or diesel fuel and a supply of gaseous fuel such as natural gas. To do that efficiently it is desirable that as little retrofitting be required as possible to existing fuel intake systems and configurations.
To this end devices have been developed for mixing natural gas and air for introduction into engines. Often these are in the form of conversion kits for installation onto carburetors. These kits convert the engine to a dual fuel system that permits operation on liquid fuel alone, on gaseous fuel alone, and in some systems on combinations of the two.
One type of such a kit includes a gaseous dispensing device mounted within an intake conduit that funnels air to the engine air filter. Exemplary of this type is that shown in U.S. Pat. No. 4,495,515. A problem associated with this type of kit is that original automobile parts must be substantially modified in order to accommodate it. Once these modifications are made the modified part must be replaced or repaired should the device be removed. Another problem associated with it is that the proper air to gas mixture is achieved through limiting the flow of gaseous fuel passing through the device into the engine air stream. This limitation results in limiting gas consumption rate throughout the entire range of gas flow rate needs.
Another type of conversion kit achieves a proper mixture of gas and air by limiting the amount of air entering the carburetor. The mixture is adjusted by increasing or decreasing air flow by typically providing a movable plate which limits the spacing through which air entering the engine may flow. The limitation of air however decreases the performance of the engine. Exemplary of these types of devices are those shown in U.S. Pat. Nos. 4,425,140, 4,425,898, and 4,387,689. Once again, these devices require substantial modifications to be made to conventional parts of the automobile engine.
Yet another type of conversion kit dispenses gas by creating a low pressure within a mixing device which causes gaseous fuel to be drawn into the airstream passing therethrough. The mixture of gas and air is adjusted by increasing or decreasing the aperture through which the gas is drawn. Exemplary of these types of devices are those shown in U.S. Pat. Nos. 5,083,547 and 5,103,795. However, today many automobiles are equipped with air-to-air cooled turbochargers which pressurize air that is then conveyed through long conduits to a radiators which cool the air prior to entering the engine. Because of the danger of rupturing these long conduits it would be extremely dangerous to mix gas with air into a combustible mixture prior to turbocharging. Also, since these devices operate at or about atmospheric pressure the pressure created by the turbocharger would make mounting these mixers downstream of the turbochargers ineffective. However, it would be highly desirable to enable a mixing device to work in conjunction with a turbocharger to attain the advantages of high performance and fuel efficiencies associated with turbocharged engines.
It thus is seen that an apparatus and process for mixing gaseous fuel and air together for introduction into a turbocharged internal combustion engine has long remained an elusive goal. Accordingly, it is to the provision of such that the present invention is primarily directed.